ELI on no trip with Megger MFT

[Simonslimline]

Does anyone have issues with this test and how accurate is a No trip test?

I find my readings seem to change a fair bit testing the same circuit a few times.

This is using a 1730.

 

[Brightspark2]

It's not just megger I find but others I've used can be so inaccurate. Get one reading then immediately press the test button again and get a completely different one!...

Instead I've started getting the apprentice to hold a pocket calculator up while I throw my screwdriver at him five times. I then use the number on screen.

Its also quicker that way!...

 

[trypod]

what is the firmware version on the Megger

 

[Simonslimline]

Im not sure it was calibrated recently and possibly updated the software maybe?

 

[Paultrim123321]

We have same issues, especially when Ze are naturally higher.

 

[Jay Sparks]

The No trip test uses a smaller current over a longer period, than the Hi test. This will useually give a higher reading. Also, the voltage will fluctuate slightley and this may also affect the result.

 

[trypod]

The No trip test uses a smaller current over a longer period, than the Hi test. This will useually give a higher reading. Also, the voltage will fluctuate slightley and this may also affect the result.

turn the right hand knob to the spanner and the left hand knob to V
it will them display the firmware version

 

[trypod]

what is the firmware version on the Megger

 

[cornishboy]

ive had a similar problem with my megger MFT1552 where I had a length of 2.5 twin and earth as a radial 3m from the mains one socket one cable got a reading of 0.98 ohms thought either corroded connection or loose conductor but not to be tested loop at mains to be 0.14 ohms very strange disconnected the RCD and got 0.23 have found since my tester does not like the new Mk sentry RCDS and they seem to add high resistance to the reading aot more than the actual value do not find this problem with starbreaker or hager

 

[FAA Greenie]

ive had a similar problem with my megger MFT1552 where I had a length of 2.5 twin and earth as a radial 3m from the mains one socket one cable got a reading of 0.98 ohms thought either corroded connection or loose conductor but not to be tested loop at mains to be 0.14 ohms very strange disconnected the RCD and got 0.23 have found since my tester does not like the new Mk sentry RCDS and they seem to add high resistance to the reading aot more than the actual value do not find this problem with starbreaker or hager

I only use MK if I need a left hand side main switch, the last two I have fitted have all added about 0.6 to any expected Zs measurements. Both times I had done Zs and R1R2 readings prior to changing the board and then got totally different readings on Zs after the event.

Rubbish.....

 

[cornishboy]

thought it was me but Mk have really fitted cheap nasty nits in their boards now and the RCDS are not compatible with trip lock loop tester readings total ********

 

[richy3333]

I wondered who was still buying MK

 

[Dizzy_Maskell]

Yes I've found on the Megger LTW model no trip gives so massively inaccurate results at times.
Seems worse the higher the earth loop would naturally be almost like it exaggerates the readings

 

[cornishboy]

try not to buy MK boards now but like someone said I needed a LH incomer and configurable so I ended up with MK never again

 

[GLENNSPARK]

thought it was me but Mk have really fitted cheap nasty nits in their boards now and the RCDS are not compatible with trip lock loop tester readings total ********

i fitted an MK board the other week...

what a load of old crap it was n all...

 

[cornishboy]

agreed, now I stick to Hager or Crabtree starbreaker have no problems and my loop readings are within acceptable values

 

[Jay Sparks]

Proteus all the way for me!!!lol

 

[tony mc]

Does anyone have issues with this test and how accurate is a No trip test?

I find my readings seem to change a fair bit testing the same circuit a few times.

This is using a 1730.

You have to remember that the MFT is only injective 15mA into the earth on the no trip so that the RCD will hold and on the HI current loop it injects 25A which will give you a more accurate reading. Some of the RCD do cause issues so if you are not happy with your results link the CPC and Line conductors out at the far end of the circuit and test on high at the CU without it going through the RCD on the isolated circuit! I have had a few issues when testing Europa and BG RCD on the no trip with a 1552 and a stand alone loop tester ! You should have a good idea what your EFLI result should be from you dead tests IMO!

 

[VoltzElectrical]

Proteus all the way for me!!!lol

British General ALL THE WAY SIR!

 

[Guitarist]

Make sure that you use the 3-wire test.